Maybe crack in the lower intake boot...very common...clean the icv...often needed. Use techron.

I'd forget the clutch being an issue. You actually described the symptoms I had at the end of my 30 mile drive with a bad alternator...running on battery only. At the end, I had to have the gas floored to have the clutch engage...the FP was pumping on its last legs I guess.

So don't forget to check your battery too. If things aren't getting enough power, you'd have issues, just like I had.

Read voltage when off and on both. You had a red battery light on first in one instance you noticed.
Check the electrical system just for grins.